With miniaturization and improvement of performance of semiconductor integrated circuits in recent years, circuits are becoming larger in scale and faster. As a result, increases in power consumption of the semiconductor integrated circuits are becoming problematic. Such a semiconductor integrated circuit is provided with a digital region section equipped with a digital circuit and an analog region section equipped with an analog circuit, and noise caused by an increase of power consumption in the digital region section roams around the analog region section, resulting in a problem of causing malfunctions or the like.
The digital circuit of the digital region section is configured by including a plurality of flip flops and a plurality of combination circuits. Furthermore, a clock signal of a predetermined frequency is supplied to the plurality of flip flops in the digital circuit from a PLL circuit or the like and the plurality of flip flops operate based on the clock signal. Switching operation of transistors in the plurality of flip flops generates current consumption at a rising edge and a falling edge of the clock signal, and therefore power consumption increases.
Particularly, power consumption when the flip flops are operating is greater at the falling edge of the clock signal than power consumption at the rising edge.